Centrifugal fan



Patented Sept. 27, 1927.

UNITED STATES OFFICE.

OEDTTBIFUGAL FAN.

Application filed October 20, 1926. Serial No. 148,842.

This invention relates to improvements in centrifugal fans withparticular reference to fans of the type commonly used for wind stackersfor threshing machines, corn huska are, etc.

The objects of this invention are to provide an im roved fan structurein which each of the wings or blades will have walls which converge fromthe inner to the outer end of w the win and re-inforce each other ;toprovide sue a fan win structure with a filler between the walls w ichwill prevent vibration and consequent crystallization and will alsoprevent the develo ment of eddy curw rents and cross currents tween thewalls of the blade or wing when in rotation ;-to provide improvedconnecting means whereby the wings may be secured to the shaft ;torovide a fan structure in which the fan may e operated with twodiametrically opposed wings revolving at slow speed with a capacity fordelivering a greater quantity of material (air and straw or othermaterial of a similar nature) than can be delivered by fans in commonuse having a greater number of wings o rative in a casing of the samediameter an under like conditions and in general to provide a fan ofincreased ca acity and durabilit and of greater cf- 80 ficiency inavoiding winding tendencies or clogging when handling wet or congestedmasses of fibrous material.

In drawings: Figure 1 is aside elevation of a fan embodymg my invention.

Figure 2 is a similar view with a side wall of the casing removed toexpose the fan blades or wings.

Figure 3 is a detail view of the wings associated with a connectedfragment of the shaft.

Figure 4 is an edge view of the wing structure shown in Fig. 3.

Figure 5 is a view similar to Figure 4, but showing a slightmodification.

, Like parts are identified by the same reference characters throughoutthe several views.

The fan casing 10 is similar to those in ordinary use for like purposesand is provided with an ordinary tangentially extending outlet tube 11.But the inlet opening 12 is formed in the side wall of the casing andhas the form of a major segment of a circle.

which includes the projected axis of the 6 shaft, the opening having astraight marginal wall 13 in a chord of said circle, which is pitchedoblique] in the general direction of the outlet. This opening allowsmaterial to enter the fan casin in the path of the fan wings at apoint were it Wlll be struck by the wings or blades and batted or caused torebound through the chute or assage 11. The fan wings are two in num erand as shown in Figures 1 to 5 they are formed of 85 a pair of elongatedplates 15 and 16 having their central ortions bolted to o posite sidesof a square s aft 17, several bo ts 18 being preferably employed. Theseplates 15 and 16 have substantially true plane surfaces and are made toconverge pro ressively toward their respective ends, there y forming apair of wedge shaped or tapering win with enter margins substantiallyparal e1 with the shaft axis and the outer marginal portions beingsecured together in an suitable manner as indicated by the row 0 rivets19 in Figure 3. The lates may, of course, be welded, or if desired, therivet heads may be counter-sunk to present a smooth surface for contactwith the material.

Wedge shaped filler blocks20 are interposed between the plates in eachwing. The inner ends of these filled blocks referably abut the shaft andtheir outer en s may extend as far as is conveniently practical towardthe extremities of the wings between the conver 'ng walls, i. 0. betweenplates 15 and 16. uitable rivets 21 connect the plates and filler blocksat intervals, and the filler blocks not only re-inforce the plates butrevent them from vibratin or from bucking under stresses imposed yimpact a ainst any hard material such as stones, sticks or pieces ofmetal contained in the straw that is being delivered through the chute.

Only two wings are provided and byemploying plates of sufiicient lengthto span the shaft and form the wings at the respective sides thereofit'becomes possible to provide a wing structure of great strength whichcan be secured to the shaft without difiiculty and which presents anunbroken surface from the tip of one wing to the tip of the opposingwing.

A wing structure of this type can be manufactured at a minimum expenseand lift ; as to cause it to doat outwardly from the llii mouth of thechute and lie fiat on the stack, whereasv ordinary centrifugal fans usedas wind staclters, not only break and tangle the straw, but deliverlarge portions thereof on end in such a manner as to direct rain waterinto the stack instead of facilitating the all building of a stack whichwill shed water. The admission of the material to the fan casing at apoint where it will be immediately struclr by one of the wings andthrown throufl the chute is an important factor contri ting to this,result.

I also find that a two wing fan having a diameter of 46 inches from thetip of one wing to the tip of the other will-be at least equalleffective for the delivery of fibrous material through the chute as afour wing fan of ordinary construction having the same diameter andwhich requires substantially twice the speed of rotation in order toapproximate the capacity of my improved fan. More specifically, it ma bestated that ordinary fans employs for wind stackers in connection withthreshing machines are four Win fans and require a speed of approximatey 900 lit. P. M. whereas my improved fan has but two wings and requiresfor the same duty a speed of 011% about 4.30 R. P. M.

eferring to Figure 5 it will be observed that the structure is the sameas that disclosed in the other views with the once tion that the portion25 of the shaft which is socured to'the fan is cylindrical and isconnected by a key 26 with a block 27 which fills the central portion ofthe space between the two plates 15 and 16 and to which the plates aresecured by sets of bolts or rivets 28 which pass through the block onopposite sides of the shaft. in this structure, the block may be of anelongated rectangular form and the filler blocks 20 will, of course, becorrespondingly shortened in pro ortion to the additional space occupiedby t e connecting block 27. The convergence of the wing plates is whollydue to the pitch of the plate which forms the working face, this featurebeing of course also available for use in the fan structure as shown inFigures 1 tea.

ll claim: l. lin a centrifugal '"an for delivering neonate straw andother solid materials in an air blast, the combination with a shaft, ofa pair of op osed wedge shaped wings, each aving su stantially trueplane surfaces which converge from the vicinity of the shaft to theouter margin of the wing.

2. In a centrifu a1 fan for delivering straw and other so id materialsin an air blast, the combination of a shaft and a single pair ofoppositely extending wings, each composed 0 metal plates spaced apartadjacent to the shaft and converging in. the direction of their outerend margins, said plates havin flat, substantially true plane surfacesan being secured together for mutual reinforcement.

3. la a centrifu al fan for delivering straw and other so id materialsin an air blast, the combination of a shaft and a single pair ofoppositel extending wings, each composed 0 meta plates spaced apartadjacent to the shaft and converging in the direction of their outer endmargins and forming true wedge sha ed'structures with said marginssubstantia y parallel to the shaft, said plates being secured togetherfor mutual reinforcement, and the space between them being provided witha filler block conforming to and filling the space which it occupiesbetween the plates and secured to the plates.

4. lln a centrifu a1 fan for delivering straw and other so id materialsin an air blast, the combination of a shaft and a pair of o positelyextending wings, each composed of flat metal plates spaced apart adacentto the shaft and converging in the direction of their outer end margins,said latte being secured together for mutual reinforcement, and thespace between them being substantially filled with non-metallic materialin re-inforcing relation to the lates and of substantially uniform thicess throu hout each transverse dimension.

5. a centrifugal fan for delivering straw and other solid materials inan air blast, the combination with a shaft having a rectangular wingsupporting portion nonrota-table with reference to the shaft, of asingle air of elongated flat metallic wing plates avin their centralortions respectively secure to opposite side faces of said rectangularwing supporting portion and end portions converging on opposite sides ofthe shaft toward a line parallel with the shaft and secured together toform generally wedge shaped win 6. lin a oentri glal fan for deliveringstraw and other so 'd materials in an air blast, the combination with ashaft having a rectan. r wing supporting portion nonrotata is withreference to the shaft, of a pair of elongated metallic wing plateshavmg their central portions respectively aslllb cured to opposite sidefaces of said supporting portion, and end portions converging onopposite sides of the shaft toward a line substantially parallel withthe shaft and secured together to form generally wedge shaped wings, anda body of nonmetallic filling material between the plates secured to theplates and adapted to reinforce them.

7. In a centrifu al fan for delivering straw and other so id materialsin an air blast, the combination with a shaft of a air of generallywedge shaped wings rigidly secured thereto, each of said wings having'flat metallic surfaces inplanes normal to the plane of rotation,converging to an outer edge margin, and a non-metallic interveningfiller ortion.

8. centrifugal fan rotor comprisin the combination of, a pair ofrectangular ates having their central portions in space relation to eachother and their end portions convergent and secured together along linessubstantially arallel to the axis of rotation, a driving and spacingmember secured to the central portions of the plates, and wooden fillerblocks conformin to the spaces between the plates on cue side of saiddriving and spacing member and secured to the plates.

WALTER B. PEDELTY.

